Interrupter system



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2,327,579- INTERRUPTER SY STEM Harold J. Brown, Indianapolis, Ind., assignor to Electronic Laboratories, Incorporated, Indianapolis, Ind., a corporation of Indiana Application January 31, 1942, Serial No. 429,074

7 Claims.

My invention relates in general to circuit converter circuits and more particularly to an arrangement to prevent the damaging of the interrupting contact. This application relates to the subject matter of my Patent No. 2,286,842 and my pending applications Serial Nos. 429,075, 429,- 076 and 429,077.

In the design of vibratory converters, substantially no difficulty is encountered in building a vibrator that is immuned to mechanical wear cn'the contact points. The impacts on closing and the wear due to rubbing can be so reduced that the device will operate indefinitely, ifat the same time, the stressed parts are properly strain-relieved and operated well below their endurance limit. With such a vibrator, the problem is primarily one of reducing the effects of the electric current and voltages on the contacts so that any required performance may be,

achieved. Experience shows that in a vibrator where the make-and-break operating cycles run into the billions, the life'and performance is ment are then charged or discharged. One of the more noticeable effects is material transfer current falls in two categories; namely, the disstrictly determined by the ability of the contact Points to withstand the pitting and erosion of the electrical current flowing at the instance of the make-and-break. Notwithstanding the fact that the most resistant materials available to the engineering art are used, the vibrator in many applications fails to meet the standards of reliability and life which are normally required. Also,

a there is need for increased power output capabilities for vibratory converters. By using larger transformers and larger vibrators, increased power has been obtained, but in general, a less satisfactory result is noted especially as regards vibrator life and reliability of the contact interruptingpoints. Vibrators with several sets of points in parallel have also been used in an effort to increase the power handling capacities, but

'here too the life and reliability of the contacts do not come up to expectations.

reason for the lack of satisfactory results lies in the character of the contacting materials when" Generally speaking,.

two or more contacts are in parallel, the final single trailing contact is subject to the attack of this The principal integration resulting from making the contact and the disintegration resulting from breaking the contact. Both may be partially controlled by the proper handling of the circuit constants but it is unfortunately true that changes in the circuit which improve the performance at the break may harm the performance at the make, and vice versa. I'herefore,'the design of a good and eiiicient converter circuit which will givelong life and reliability against breakdowns presents a difficult problem to solve and a satisfactory circuit cannot be prescribed on the basis of a superficial examination. Furthermore, the absence of sparking is no criterion of a satisfactory circuit, as it is often true that the performance of mildly sparking contacts will be superior to dark ones. A further characteristic of contact points is'that various thresholds of current exist below which material transfer and high'current density. Similar destructiye effects 7 take place when the contact engagement is made,

erosion do not occur at all or in small amounts.

An object of my invention is, therefore, the provision of reducing the electrical disintegration effect below the threshold valuewhere material transfer and erosion do not occur at all or in small amounts.

Another object of my invention is to prevent the current flowing through one contact from diverting into another, as one contact is opened prior to another.

Another object of my invention is to forcibly prevent the current flowing in two or more vibrator contacts from re-establishing itself in a single final trailing contact tip during the short interval-of time involved between the successive openings of the parallel contacts and to insure that the burden of interrupting the circuit is divided between the pair of parallel contacts.

' Another object of my invention is the proviruptions, of the plurality of interrupting paths from suddenly re-esta-blishing itself in a yetuninterrupted path during the short interval of time.

involved between the successive interruptions of .the parallel paths.

Another object of my invention is to keep the flow of the interrupting current in the interrupting contacts less than that certain threshold value below which material transfer and erosion of the contacts do not occur at all or in small amounts.

In a set of parallel contacts, the current will divide between the contacts according to Ohms law. Since the contact resistance is small compared to the rest of the vibratory circuit, which ,is ordinarily the case, the opening of one of two parallel contacts will not effect the total current now, and the total current will then flow through the remaining closed trailing contact. The time required for this diversion will be very small, perhaps less than seconds, as indicated by the residual inductance. and resistance of the closed loops through the two parallel Contacts. In any practical vibrator, the differences in opening time may be a thousand times this value so the problem maybe stated as one of increasin the diversion time perhaps a thousand or more times its ordinary value. v

Therefore, another object of my invention is to provide for increasing the diversion time per-- haps a thousand or more times its ordinary value. Another object of my invention is to utilize the ordinary primarybufier condenser as a current-diverting condenser during the short in- 6? are connected in parallel through a first circuit connection means comprising a common conductor 3| and two branch circuits 32 and 33. The right-hand end of the common conductor 3| is, connected to the end M of the primary winding E2 of the transformer. The two oppositely disposed contacts 29 and 22 on the other side of the vibrating reed H are connected in parallel through a second circuit connection means comprising a common conductor 34 and two branch circuits 35 and 36. The right-hand end of the common conductor 34 is connected to the end I5 of the primary winding l2 of the transformer. Mounted respectively in the branch circuits 32 and 33 of the first circuit connection means are windings 6| and 43 on the inductances-39 and M].- Mounted in the two branch circuits 35 and 36 of the second circuit connection means are two windings 42 and 44 on the inductances 39 and 40. As illustrated, the windings ll and 42 of the inductance 39 are mounted upon a core 45 having an air gap 41 and similarly the windings A3 and 44 of the inductance 40 are mounted upon a core 46 having an air gap 48.

In operation, the parallel contacts l9 and 2|! on one side of the vibrating reed |1 provide for "interrupting the current which flows through terval of time involved between the successive openings of the contact members to avoid the use of by-pass condensers in the circuit.

Another object of my invention ,is to divide the primary buffer condenser into two parts and thus reduce the condenser efiects on the making of the contacts.

Another object of my invention is to 'reduce the electrical damage to the contacts during both the "make and break cycles thereof.

Other objects and a fuller understanding of my invention may following description junction with the ac'cbmpanying drawing, in which:

, The figure constitutes be had by referring to the the single view of a vi- 'bratory circuit involvingthe features of my m v vention.

with reference'to the drawing, my invention comprisesin general a'vibratory interrupter ill, a transformer two capacitors 29 and'3fl, and two inductances 39 and 40. As illustrated, the vibratory'interrupter supplies an interrupted direct current to the primary winding l2 of the transformer H which in turn supplies an alternatlng current winding is connected to one side 25 of the direct current source and the other side 25 of the direct current source is connected to the vibrating reed H of the vibratory interrupter. As shown, the vibratory interrupter comprises twoparallel sets of interrupting contacts, in which one set comprises the oppositely disposed contacts l9 and 28' setof contacts. -The oppositely disposed conl9 and 2| on one side oi the vibratin reed and claims, taken in con-' to the load from the secondary I winding Hi. The center-tap |3 of the primary the upper half of the primary winding.|2 and the two parallel contacts 20 and 22 on the other side of the vibrating reed provide for interrupting the current which flows through the bottom half of the primary winding |2. If it be assumed that the contact l9 breaks before the contact 2|, then the current flowing through the contact l9 will tend to re-establish itself in the contact 2| but the winding 4L0 the inductance. 39ldevelops in series with't e contact 2| an inductive impedance to oppose the sudden re-establishment -of the current which formerly flowed through into. In other words, the combined action of the capacitor 30 and the winding 4| on the inductance 39 prevents. the re-establishment of the current from the interrupted contact |9 through the yet uninterrupted contact 2| during the short successive openings interval of time between theof the contacts I9 and 2|. Under the assumption that the contact 2| opens before the contact l9, then the reverse action of the capacitor 29 and the winding 43 on the inductance 40 prevents the current in the interrupted contact 2|-from suddenly re-establishing itself in the yet uninterrupted contact l9 during the short interval of' time involved between the successive opening of the contacts 2] and Hi. The operation of the contacts 2|! and 22 is the same as that just described for the contacts I9 and 2| in that should the contact 2fl break before the contact 22 then the winding on the inductance 39 in combi-:' nation with the actionof the capacitor 30 prevents the interrupted current in the contact 30 from suddenly re-establishing itself in the un interrupted contact 22 during the short interval of time involved between the'successive openkiss of the contacts 20 and 2 I. Similarly, in the event'that the contact 22 breaks before the conl the contacts tact 20, then the winding 44, in combination with the capacitor 29, prevents the interrupted current in the contact22 from suddenly re-establishing itself in the yet uninterrupted contact during the short interval of time involved between the successive openings of the contacts 22 and 20.

In my circuit as illustrated, the capacitors 29 and 30 are buffer condensers commonly used in vibratory circuits but I also use them as current- I diverting condensers during the short interval of time involved between the successive openings of In addition, the capacitors 29 and 30 are each substantially one-half the capacity of what a condenser would be if it were connected across a vibratory converter having but a single set of oppositely disposed contacts. Therefore, in regard to the making of the circuit, it will be noted that the condenser effect is divided in half, the capacitance of the condensers 29 and 30 totalling what; would normally be the entire primary buiier condenser. This means that the condenser energy on the make contact is halved and its eifect reduced- Consequently, in

my invention Iprovide for reducing the damage to the contact upon both the make and the "break cycle of interrupting contacts.

Since the windings upon the inductances 39 and 40 must carry the primary load current, I preferably make the magnetic cores 45 and 46 thereof with the air gaps 41 and 48 with the result that the magnetizing current for the inductances 39- i the windings thereon. Accordingly, the cores with the air gap provide a' very useful way in the design of my circuit in that the opposition efiect of the winding may be made sufficient to take care .of the division of th current between the two parallel contacts while at the same time avoiding the presence of too much impedance in the primary load circuit to interfere with the total efliciency of the circuit.

The windings 4i and 42 upon the inductance 39 and the windings 43 and 44 upon the inductance 40 are so magnetized that the flux condition produced by the-pairof windings on each core is additive when the current flows through the capacitors 29 and 30 immediately subsequent to the opening of the contacts of the vibratory interrupter. The foregoing statement may be illuminated by describing the flow of the currentthrough' the windings 42 and 44 upon the inductance 40 upon the breaking of the contact I9, whereupon the current begins to flow immediately in a looped circuit comprising the capacitor 30, the winding 44 upon the inductance 40, the entire primary winding 12 of the transformer, the winding 43 on the inductance 40 back to the condenser. The flow of the current in the loop circult just described through the windings 4t and 49 is in the opposite direction, but the turns of the windings are in the opposite direction so that the net eflect of the inductance is additive immediately subsequent to the breaking of the conrangement for preventing th current which is interrupted in an interrupted parallel contact path incident to slight variations in the breaking of the plurality of set of contact means from suddenly re-establishing itself in a yet uninterrupted parallel contact path during the short interval time involved between the successive openings of the contact means to prevent the damaging of the contacts. My invention also reduces the damaging to the contacts during the "making" cycle in that the primary buffer condenser is divided into two parts wh rein both parts when taken together make up the entire primary buffer condenser, wherein the condenser energy upon the make contact isreduced to onehalf its value where the primary buffer condenser is not divided. The reduction in the condenser energy reduces the effect of the damage to the contacts during the making thereof.

While I have illustrated and described my invention as having particular utility in connection with interrupting parallel contacts, it is to be understood that my invention is not limited thereto and, herefore, includes any interrupting system comprising interrupting means having a plurality of parallel interrupting paths which are substantially simultaneously interrupted for jointly interrupting the current in the electrical system.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of constructionand the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. In an electrical system for converting current from a direct current source into alternating current and supplying the latter to a load, said system comprising a transformer having primary winding means with two ends and a center tap and secondary winding means supplying the alternating current to the load, and a vibratory interrupter having a plurality of interrupting sets of parallel contact means substantially simultaneously operated during a vibratory interval for jointly supplying an interrupted direct current through a plurality of parallel contact paths to the primary winding means of the transformer, each set of parallel contact means including oppositely disposed contact means and vibratory contact means operating therebetween, said center tap being connected to one side of the direct current source and said vibratin contact means being connected to the other side of the direct current source, a plurality of first circuit connection means each connecting one of said oppositely disposed contact means of each set of parallel contact means to one end of the primary winding means and a plurality of second circuit connection means, each connecting the other of said oppositely disposed contact means of each set of parallel contact means to the other end of the primary winding means; the arrangement for preventing the current which is interrupted in an interrupted parallel contact path incident to slight variations in the breaking of the plurality of sets of contact means from suddenly re-establishing itself in a yet uninterrupted parallel contact path during a vibratory interval of the breaking of the plurality of sets of contact means, said arrangement comprising the combination of a capacitor connected across the oppositely disposed contact means of each set of parallel contact means, and inductance means included in each of the plurality of first and second circuit connection means for developing, in series with each of the sets of parallel contact means, an inductive impedance to the fiow of the current therein, the inductive impedance in the yet uninterrupted parallel contact path opposing the sudden 're-establishment of the current of an interrupted parallel contact path during a vi -bratory interval in the yet uninterrupted parallel contact path, thereby preventing the damaging of the contact means.

2. In an electrical system for converting current from a direct current source into altemating current and supplying the latter to a load, said system comprising a transformer having primary winding means with two ends and a center tap and secondary winding means supplying the alternating current to the load, and a vibratory alternating current to the load, and a vibratory interrupter having a plurality of interrupting sets of parallel contact means substantially simultaneously operated during a vibratory interval for jointly supplying an interrupted direct current through a plurality of parallel contact paths to the primary .winding means of the transformer, each set of parallel contact means in.-

cluding oppositely disposed contact means andvibratory contact means operating therebetween, said center tap being connected to one side of the direct current source and said vibrating conv tact means being connected to the other side of interrupter having a plurality of interrupting sets of parallel contact means substantially simultaneously operated during a vibratory interval for jointly supplying an interrupted direct current through a plurality of parallel contact paths to the primary winding means of the transformer, each set of parallel contact means including oppositely disposed contact means and vibratory contact means operating therebetween,

said center tap being connected to one side of the direct current source and said vibrating contact means being connected to the other side of the direct current source, a plurality of first circuit connection means each connecting'one of said oppositely disposed contact means .of each set of parallel contact means to one end .of the primary winding means and a plurality of second circuit connection means, each connecting the other of said oppositely disposed contact means of each set of parallel contact means to the direct current source, a plurality of first cir-' cuit connection means each connecting one of said oppositely disposed contact means of each set of parallel contact means to one end of the primary winding means and a plurality of second circuit connection means, each connecting the other of said oppositely disposed contact means of each set of parallel contact menas to the other end of the primary winding means; the arrangement for preventing the current which is interrupted in an interrupted parallel contact path incident to slight variations in the breaking of the plurality of sets of contact means from suddenly re-establishingitself in a yet uninterrupted parallel contact path during a vibratory interval the other end of the primary winding means; the

arrangementfor preventing the current which is interrupted in an interrupted parallel contactv with a first and a second winding means thereon,

said first winding means of the plurality of inductance means being included respectively in each of the first circuit connection means and l of the current of an interrupted parallel contact said second winding means of the plurality of in- I ductance means being included respectively in each of the second circuit connection means ior developing, in series with each of the sets of parallel contact means, an inductive impedance to the flow of the current therein, the inductive impedance in the yet uninterrupted parallel contact path opposing the sudden re-establishment.

of the current of an interrupted parallel contact path during a vibratory interval in the yet uninterrupted parallel contact path, thereby preventing the damaging of the contact means.

.3. In an electricalsystem for converting current from a direct current source into alternati current and supplying the latter to a load,

' said system comprising a transformer havingp'rimary winding means with two. ends and a center tap and secondary winding means supplying the of the breaking of the plurality of sets of contact means, said arrangement comprising the v combination of a capacitor connected across the oppositely disposed contact means of each set of parallel contact means, and a plurality of inductance means, eachcomprising a common core with a, first and 'a second winding means thereon, said first winding means of the plurality of inductance means being included respectively in each of the first circuit connection means and said second winding means of the plurality of inductance means being included respectively in each of the secondv circuit connection means for developing, in series with each-of the sets of parallel contact means, an inductive impedance to the fiow of the current therein, the inductive impedance in the yet uninterrupted parallel contact path opposing the sudden re-establishment path during a vibratory interval in theyet uninterrupted parallel contact path, thereby preventing the damaging of the contact means; said first and said second winding means of eachinductance means producing an additive flux condition in the common core. I

4. In an electrical system for converting current from a direct current source into alternating current and supplying the latter to a load, a

said system comprising a transformer having prim'ary winding means with two ends and a center tap and secondary winding means supplying the alternating current to the load, and a vibratory interrupter having a plurality of interrupting sets of parallel contact means substantially simultaneously operated during a vibratory interval for jointly-supplying an interrupted divibratory contact means operating therebetween, said center tap being connected to one side of the'direct currentsource, a plurality or first cirrect current through a plurality of parallel contact paths to the primary winding means of the.

transformer, each set of parallel contactmeans including oppositely disposed contact means and the direct current source and said vibratingcon tact meansibeing connected to the other side of cuit connection means each connecting one of said oppositely disposed contact means of each of the plurality of sets of contact means, said arrangement comprising the combination of a capacitor connected across the oppositely disposed contact means of each set of parallel contact means, and a plurality of inductance means, each comprising a common core with an air gap and with a first and a second Winding means thereon, said first winding means of the plurality of inductance means being included respectively in each of the first circuit connection means and said second winding means of the plurality of inductance means being included respectively in each of the second circuit connection means for developing, in series with each of the sets of parallel contact means, an inductive impedance to the flow of the current therein, the inductive impedance in the yetuninterrupted parallel contact path opposing the sudden re-establishment of the current of an interrupted parallel contact path during a vibratory interval in the yet uninterrupted parallel contact path, thereby preventing the damaging oi the contact means.

5. In an interrupter system having a plurality of electrical connections and interrupting means for interrupting a plurality of groups of parallel interrupting paths, the parallel paths of each interrupting group comprising a plurality of paths.

and being substantially simultaneously interrupted by the interrupting means for jointly interrupting the current in the system, said interrupting paths of said groups being also arranged to constitute a plurality of sets of interrupting paths, a plurality of circuit connection means, each respectively interconnecting the plurality of groups of interrupting paths to the plurality of electrical connections, the arrangement for preventing the current which is interrupted in an interrupted parallel path of a group incident to slight variations in the interruption of the parallel paths of the group from suddenly re-establishing itselfin a yet uninterrupted parallel path and increasing the burden on the said yet uninterrupted parallel path during the short interval involved between successive interruptions of the parallel paths of a group, said arrangement comprising current-diverting means connected across each set of said interrupting paths, and inductance means included in each of the plurality of circuit connection means for developing, in series with each of the interrupting paths of said groups, an inductive impedance to the flow of the current therein, the inductive impedance in'the yet uninterrupted parallel path in combination with the current-diverting means opposingthe sudden-re-establishment of the current of an interrupted parallel path of a group during the short interval involved between \the successive interruptions ofthe parallel paths of the group in the yet uninterrupted path,

thereby prve'nting the damaging of the interrupting means.

6. In an interrupter system having a common circuit, a plurality of electrical connections, and interrupting means for interruptingly connecting a plurality of groups of parallel interrupting paths to the common circuit, the parallel paths of each interrupting group comprising a plurality of paths and being substantially simultaneously interrupted by the interrupting means for jointly interrupting the current in the system, said interrupting paths of said groups being also arranged to constitute a plurality of sets of interrupting paths with the common circuit therebetween, a plurality of circuit connection means, each respectively interconnecting the plurality of groups of interrupting paths to the plurality of electrical connections, the arrangement for preventing the current which is interrupted in an interrupted parallel path of a group incident to slight variations in the interruption of the parallel paths of the group from suddenly re-establishing itself in a yet uninterrupted parallel path and increasing the burden on the said yet uninterrupted parallel path during the short interval involved between successive interruptions of the parallel paths of a group, said arrangement comprising current-diverting means connected across each set of said interrupting paths, and inductance means included in each of the plurality of circuit connection means for developing, in series with each of the interrupting paths of said groups, an inductive impedance to the flow of the current therein, the inductive impedance in the yet uninterrupted parallel path in combination with the current-diverting means opposing the sudden re-estaolishment of the current of an interrupted parallel path of a group during the short interval involved between the successive interruptions of the parallel paths of the group in the yet uninterrupted path, thereby preventing the damaging of the interrupting means.

7. In an interrupter system having a plurality of electrical connections and interrupting means for interrupting a plurality of groups of parallel interrupting paths, the parallel paths of each interrupting group comprising a plurality of paths and being substantially simultaneously interrupted by the interrupting means for jointly interrupting the current in the system, a plurality of circuit connection means, each respectively interconnecting the plurality of groups of interrupting paths to the plurality of electrical connections, the arrangement for preventing the current which is interrupted in an interrupted parallel path of a group incident to slight variatlons in the interruption of the parallel paths of the group from suddenly re-establishing itself in a yet uninterrupted parallel path and increasing the burden'on the said yet uninterrupted parallel path during the short interval involved between successive interruptions of the parallel paths of a group, said arrangement comprising currentdiverting means connected in efiective electrical current-diverting relationship with the interrupting paths of said groups, and inductance means included in each of the plurality of circuit connection means for developing, in series with each of the interrupting paths of said groups, an inductive impedance to the flow oi the current therein, the inductive impedance in the yet uninterrupted parallel path in combination with the current-diverting means opposing the sudden re-establishment of the current of an interrupted parallel path of a group during the short interval involved between the successive interruptions of the parallel paths of the group in the yet uninterrupted path, thereby preventing the damaging of the interrupting means.

HAROLD J. BRowN. 

